Drill cutter retaining means



May 5, 1931. F, L, SCQTT DRILL GUTTER RETAINING MEANS fitto: m

Filed Dec. 16, 1925 Patented May 5, 1931 UNITED ,STATES PATENT OFFICE FLOYD L. SUOTT, OF HOUSTON, TEXAS, ASSIGNOB TO HUGHES TOOL UOIPANY, OF HOUSTON, TEXAS, A. CORPORATION F TEXAS Darm. corran. maremma ums Application med December 16, 1925. Serial No. 75,709.

My invention relates to means for retaining a rotatable earth boring drill cutter in position upon its bearings.

In the cone type of earth horing drill now u in common use in the drilling of deep oil wells, the cutters are mounte upon downwardly inclined pins or shafts, and, as the cutters surround the forward ends of the pins,

or the hearings, especial means must be pro- 1a vided to retain the cutters from removal from the pin during operation.

It is an object of my invention to provide a cutter retaining device for rotary earth boring drills which will allow a simplied :it shape for the cutter and its bearin ls, whereby the wear upon `the cutter an bearing will be uniform.

It is also 'an object to construct a drill cutter retaining means, which will be auto-` tt matically locking and not again liable to become loosened or broken.

Referring to the drawings herewith, Fig. l is a broken view of the lower end lof an earth horing drill embodying my invention, M one of the cutters thereon being shown in central verticalsection. Fig. 2 is a transverse section on the line 2 2 of Fig. 1. Fig. 3 is a central section through a cutter showing a slightly diderent embodiment of the inven tion. Like numerals of reference designate like parts in both the views.

In Fig. 1, the lower end of a bit head l is shown. Said head is split longitudinally along the line 2, so as to allow the assembly of the cutters upon their shafts more readily. 'llhe forward end ofthe head has a notch or recess of the shape of an inverted V thus providing two inclined faces 3 diverging downwardly. 'Ihe shafts 4 project from the lower ends of each of these faces, as shown in Fig. l, so as to converge downwardly.

Each cutter shaft fl is threaded at 5 for the major portion of its length, the forward end 6 being reduced in diameter and not threaded. l A

A bearng'bushing 7 is screwed upon the shaft l. Said hearing bushing is frustoconical in general shape, theY interior being formed to receive the shaft, the end of which it surrounds. The edge of the bushing, at

its base is beveled olf at 8 and a plurality of recesses 9 are formed therein to receive a wrench, or similar tool, whereby the bushing magnbe screwed upon the shaft.

a transverse plane spaced from the base of the bushing 7 I cut an annular groove or recess 10 to receive a spring locking ring 11. I have shown said groove as being cut in a direction perpendicular to the axis of the shaft d, but it may, if desired, be cut at right angles to the line of the surface of the bushhe cutter l2, is a frusto-conical shaped shell, shaped to fit upon the bushing 7, and has an interior groove 13 adapted to register with and to receive the locking ring ll. Said ring 11 is of resilient metal, such as steel, and is s lit at one point. It tends to spring outwar y to t within the groove in the cutter. It will be noted that the groove 10 in the bushing is deep enough to receive the entire ring 11, but the groove in the cutter will receive only about one half the thickness of the ring, so that when the cutter is forced over the bushing with the ring 11 in the groove l0, the ring will be forced into said groove until the groove 13 in the cutter passes over the said ring, whereupon it will spring out into locking position shown in Eig. 1, thus preventing removal of the cutter. When in locked position, the larger end 14 of the cutter projects slightly beyond the base 8 of the bushing so as to cut space for the drill head within the hole.

The outer face of the cutter may be toothed in any desired manner, and I have shown longitudinal teeth l5 thereon, as is common. The bearing surface may be lubricated if desired and an oil duct 16 is shown through the shaft l, and the bushing whereby oil from a lubricator chamber, not shown, may be fed to the bearing.

As shown, the bearing surface 17 between the bushing and the cutter is nearly horizontal at'the lower side. The weight of the drill 'and drill stem. is vertically downwardly, so that it will be received along the line 17 of the cutter with very little tendency to tilt the cutter upon the bearing. The wear will hence 100 be uniform between the lower face of the bushing and the inner wall of the cutter.

In this embodiment it is not intended that the cutter shall be again removed from the bushing, and as' the bushing will ordinarily Wear as long as does the cutter, both may therefore be discarded when the cutting surface of the cutter is worn out.

In Fig. 3, I have illustrated an embodiment of the invention wherein the cutter may be removed from the bearing whenever it becomes desirable. This is accomplished by making the bushing 7 in two sections one part being a removable ring 18 screwed upon the base of the main bushing 7 which is threaded at 19 to receive it. The bushing ring 18 extends inwardly to the further edge of the locking ring groove 13 in the cutter 12. The removable portion 18 of the bushing has a recess therein to form part of the groove 10 which receives its portion of the locking ring 11.

The ring 11 may be a single piece ring as in the Fig. 1 embodiment but it need not depend upon its resiliency to hold it in the cutter groove, as the bushing ring fits firmly against it, locking it in place. It is also to be noted that the groove 13 in the cutter need be deep enough to receive one-half of the thickness only of the ring 11. The ring 11 may also be made in sections, if desired, shaped to fit the groove 13.

The two bushing sections 7 and 18 may be locked, if desired, by the welding of a small amount of metal 20 into a space between them as shown. This metal may be again removed with a blow torch if it is desired to remove the cutter from its bushing.

The advantages of this construction will be apparent to those skilled in the art. The cutter may be made more cheaply; it may be more quickly assembled upon its bearing, and the simplified shape of the cutter allows for even uniform wear between the cutter and the bushing, which materially prolongs the life of the bearing and the cutter as well.

What I claim as new and desire to protect by Letters Patent is:

1. In a drill cutter, a frnsto-conical shaped bushing formed to surround the end of its supporting shaft, a toothed cutter shaped to fit upon said bushing, registered grooves in the bearing surfaces of said bushing and cutter spaced between the forward end and the base and a resilient locking ring fitting within said grooves to prevent longitudinal movement of said cutter on said bushing during operation.

2. In a drill cutter, an approximately frusto-conical shaped bushing, having an annular ring-receiving groove in its-periphery and spaced from the ends thereof, a toothed cutter having its interior bearing surface shaped to fit over the end of saidV bushing, there being a groove formed in the said interior bearing surface to register with the groove in said bushing, and a locking ring in said groove.

3. In a drill cutter a bushinvr having a forwardly tapered bearing sur ace, a cutter fitting over the forward tapered end thereof,

and resilient means between the forward end and the base of said tapered surface to secure said cutter against longitudinal movement on said bushing.

4. In a drill cutter, a bushing having a forwardly tapered bearing surface, a cutter ttiug over the forward tapered end thereof, and means on said tapered bushing to automatically engage said cutter and lock it against removal from said bushing when said cutter is fitted over said bushing.

5. In a drill cutter a bushing tapered forwardly, a toothed cutter shapedjo fit rotatably upon said bushing, and mea'is intermediate the ends of said bushing to engage said cutter and automatically lock said cutter rotatably thereon.

6. In a drill cutter, an approximately frusto-conical shaped bushing having a cir cumferential groove along its tapered face spaced from the base thereof, a cutter on said bushing having an inner annular groove adapted to register with said groove in said bushing, and a resilient ring fitting closely in said grooves.

7 In a drill cutter, a frusto-conical shaped bushing adapted to be screwed over the end of a cutter shaft, a cutter shaped to fit over and surround the end of said bushing, saidbushing being accessible beyond the base of said cutter to receive a wrench, and means engaging between said cutter and bushing on the tapered surface thereof, to secure said cutter rotatably upon said bushing.

8. In a drill cutter, a bushing adapted to be screwed upon a su porting shaft to surround the end thereo a cutter ttin over the end of said bushing, means to loc said cutter rotatably thereon, said bushing being accessible beyond the base of said cutter to receive a wrench, whereby said cutter and bushing can be screwed upon said shaft when said cutter and bushing are locked together.

9. In a drill cutter, a bushing adapted to be screwed upon a cutter shaft to surround end thereof, a cutter shaped to fit over the end of said bushing and having a bearing thereon, means whereby said cutter is locked rotatably on said bushing, said bushing being notched beyond the base of said cutter for engagement with a wrench whereby said bushing and cutter may be rotated upon said shaft.

10. In an earth boring drill including a drill head and a shaft on said head, the combination of a bearing fixed on said shaft, a cutter shaped to enclose the end of said bush- 1ng, and means engaging said bushing and iis cutter between the ends thereon rotatable with said cutter, and enclosed and concealed by said cutter, to hold said cutter rotatably on said bearing.

11. A cutter for earth boring drills, including a bushing adapted to be secured upon a drill shaft, said bushing having an* approximately frusto-conical bearing periphery, a cutter shaped to t over said bushing, and means spaced from the base of said bushing and automatically engaging the inner bearing surface of said cutter to lock said cutter rotatably on said bushing when said cutter is fitted upon said bushing.

l2. In a drill cutter, an approximately frusto-conical shaped bushing, having an annular ring-receiving groove in its'periphery, a toothed cutter shaped to fit over said bushing, there being a groove in its interior bearing surface to register with the groove in said bushing and a locking ring in said groove and entirely enclosed by said cutter and bushmg.

13. In an earth boring drill cutter, a frusto conical bushing, a cutting element ittin@r over and surrounding the forward end ofa said bushing, said cutting element and said bushing having grooves on their meeting surfaces spaced from the base thereof, and a locking ring therein adapted to automatically secure said cutter upon said bushing when said cutting element is seated on said bushing.

In testimony whereof, I hereunto afx my signature, this the 4th day of December, A. D.

FLOYD L. SCOTT.` 

